It's probably not wise to say much more. (Not easy, either -- the plot's both confusing and familiar, and if I told you the old sci-fi movie it borrows from, it would give the rest away). Basically, it takes two innocents and maneuvers them into a situation where they're blackmailed into helping the bad guys, pursued as terrorists by the good guys, and spied on by both at every turn.

Then it punctuates the scenes with the kind of special-effects explosions only a Michael Bay could love.

"Eagle Eye" is big, loud, expensive and not particularly entertaining. Shia LaBeouf is the hero, but he remains little more than a pleasant presence. As the heroine, Michelle Monaghan is painlessly forgettable.

There's more juice, as there often is, in the supporting roles. Billy Bob Thornton has two or three good scenes as a snarling FBI investigator; Rosario Dawson gets to stay buttoned-up for once as a naval intelligence agent striding around and barking orders. (Although she would have added even more life to the film if she played Monaghan's part.)

But the central conceit -- which consists of LaBeouf's cell ringing all the time to give him orders -- gets tiresome. And the breadth of the technological conspiracy -- with the villain able to not only broadcast messages to specific TV screens, but to overload a high-tension wire just in time for it to collapse and electrocute someone -- is absurd.

Stretching the limits of plausibility is allowable. In films like "North by Northwest," Hitchcock did it constantly, but the master knew how important stars were in suspending our disbelief (and how trivial the actual nuts-and-bolts detail of the movie conspiracy was). Director D.J. Caruso, who directed LaBeouf in "Disturbia, and his four credited screenwriters don't.

The movie is so huge its small characters get lost in it. It's a shame because there's a definite chill to its central idea of being watched all the time.